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Analytical Cellular Pathology
Volume 14 (1997), Issue 1, Pages 51-59

Sequential Assessment of Cell Cycle S Phase in Flow Cytometry: A Non-Isotopic Method to Measure Lymphocyte Activation In Vitro

Ch. Kohler,1 M. N. Kolopp‐Sarda,1 A. De March‐Kennel,1 A. Barbaud,2 M. C. Béné,1 and G. C. Faure1

1Laboratoire d’Immunologie, JE DRED 251, Faculté de Médecine & CHU de Nancy, France
2Service de Dermatologie, CHU de Nancy, Nancy, France

Received 28 November 1996; Revised 5 March 1997; Accepted 19 March 1997

Copyright © 1997 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Lymphocyte multiplication can be induced in vitro by mitogens or specific antigens, and is usually measured using isotopic methods involving tritiated thymidine. Cellular proliferation can also be analyzed by flow cytometry techniques based on cell cycle analysis through the measurement of DNA content. We applied this method to lymphocytes from 113 individuals, to evaluate lymphocyte proliferation after stimulation in vitro by a mitogen (phytohaemagglutinin, PHA) or a recall antigen (tetanus toxoid), using a kinetic approach with four points sequential measurements of the S and G2 phases over six days of culture. The proportion of cells in S phase after PHA stimulation was significantly higher than in controls overall and as early as on day three of the culture. Activation with a recall antigen significantly induced increasing S phase cell proportions up to day six. These data suggest that flow cytometric assessment of the S phase could be a useful alternative to isotopic methods measuring lymphocyte reactivity in vitro.